Cancer is a heterogeneous disease characterized by divergent biological and clinical behaviors with different outcomes in different patients in apparently similar pathologic settings (Iwamoto, T., Pusztai, L. 2010. Genome Med. 2: 81). Subtle differences in the gene expression and processing of RNA molecules by otherwise undistinguishable tumors can underscore substantial differences in the prognostic outcome, in particular its recurrence and responsiveness to therapy (Ravo, M. et al. 2008. Lab. Invest. 88: 430-40).
RNA expression profiling may be very useful for the discovery and validation of biomarkers for cancer (as well as for other diseases), for tumor classification, for understanding the mechanisms of disease progression, for optimizing treatment for individual patients (e.g., identification of companion diagnostics) and for assessing progress during treatment).